EARNINGS PER SHARE (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Earnings Per Share
Net income available for stockholders:	$ 72,260	$ 73,165	$ 153,015	$ 138,689
Less: Dividends paid
Common stock	(17,191)	(10,261)	(34,436)	(20,432)
Restricted shares of common stock	(321)	(65)	(647)	(248)
Undistributed earnings	54,748	62,839	117,932	118,009
Allocation of undistributed earnings:
Common stock	53,618	61,558	115,497	115,603
Restricted shares of common stock	$ 1,130	$ 1,281	$ 2,435	$ 2,406
Basic shares outstanding:
Common stock	210,331	213,266	210,683	213,089
Restricted shares of common stock	4,562	4,556	4,558	4,583
Basic shares outstanding total	214,893	217,822	215,241	217,672
Diluted shares outstanding:
Common stock	210,331	213,266	210,683	213,089
Dilutive effect of options	1,234	2,440	1,539	2,804
Weighted average number of diluted shares outstanding including common stock and dilutive effect of stock option	211,565	215,706	212,222	215,893
Restricted shares of common stock	4,562	4,556	4,558	4,583
Basic and diluted shares outstanding total	216,127	220,262	216,780	220,476
Common stock:
Distributed earnings	$ 0.08	$ 0.05	$ 0.16	$ 0.10
Undistributed earnings	$ 0.26	$ 0.29	$ 0.55	$ 0.54
Basic earnings per share total	$ 0.34	$ 0.34	$ 0.71	$ 0.64
Restricted shares of common stock:
Distributed earnings	$ 0.07	$ 0.01	$ 0.14	$ 0.05
Undistributed earnings	$ 0.25	$ 0.28	$ 0.53	$ 0.53
Earnings per share basic restricted shares of common stock	$ 0.32	$ 0.29	$ 0.67	$ 0.58
Common Stock:
Distributed earnings	$ 0.08	$ 0.05	$ 0.16	$ 0.09
Undistributed earnings	$ 0.25	$ 0.28	$ 0.55	$ 0.54
Diluted earnings per share total	$ 0.33	$ 0.33	$ 0.71	$ 0.63